Hydraulically operated offset cutter

ABSTRACT

A hydraulically operated offset cutter having a hydraulic circuit driving a cylinder for raising, lowering or stabilizing the position of a hydraulically driven cutter driven from the same pump as said cylinder piston. The cylinder circuit has a uniquely provided control valve to accomplish the selective operations of raising, lowering or stabilizing the hydraulically driven cutter. The control valve contains a bypass line containing one or more pressure-restricting orifices for passing oil to the motor under conditions when the control valve provides useful flow of oil to a piston for raising or lowering the offset cutter, enabling the motor to continue operating. Thus a back pressure builds up behind the orifices and the oil is directed by the control valve to the cylinder piston causing it to operate as desired.

O United States Patent I 1 1 3,729,910 Hardee 1 -May 1, 1973 HYDRAULICALLY OPERATED OFFSET CUTTER Primary Examiner-Russell R. Kinsey [76] Inventor: Eldred V. Hardee, Mount Vernon, Atmmey Kelth MSegades et Route 4, Lors, SC. 29569 5 ABSTRACT [22] Flled: 1971 A hydraulically operated offset cutter having a [21] A pl, NQ; 200,388 hydraulic circuit driving a cylinder for raising, lowering or stabilizing the position of a hydraulically driven cutter driven from the same pump as said cylinder [52] US. Cl ..56/ll.9, 56/152 piston The cylinder circuh has a uniquely provided [51] Illt. Cl. ..A01d 69/00 control valve to accomplish the Selective operations of [58] Fleld of Search ..56/l0.8, 10.9, I 1.9, raising, lowering or Stabilizing the hydraulically driven 56/152 16-2; 60/52 52 HE cutter. The control valve contains a bypass line containing one or more pressure-restricting orifices for [56] Rderences Cited passing oil to the motor under conditions when the UNITED STATES PATENTS control valve provides useful flow of oil to a piston for ralsmg or lowering the offset cutter, enabling the 2,953,164 9/1960 Haberland et a1. ..56/l0.9X motor to continue operating. Thus a back pressure 2,976,663 3/ 1961 Smith et a]. ..56/ 10.7 builds up behind the orifices and the oil is directed by 3,087,296 4/1963 Cowles ..56/|0 7 the control valve to the cylinder piston causing it to 3,3 I 9,407 5/1967 Jordan l. 3L. ..56/l0 7 operate as desired 3,548,570 12/1970 Knott et al..,. ....56/104 3,559,385 2/1971 Eaton ..56/10 7 10 Claims, 3 Drawing Figures Patentd May 1, 1973 r 7 3,729,910 I 1 3 Sheets-Sheet 1 ELDRED V.. HARDEE fINVENTOR- ATTORNEY? Patented May 1, 1973 'v 3,729,910

3 Sheets-Sheet 2 INVENTOR ELDRED v HARDEE Patented May 1, 1973 T 3,729,910

3 Sheets-Sheet 5 FIELD OF THE INVENTION The present invention relates to a new and improved hydraulic circuit for a pivotally mounted offset cutter apparatus, and more particularly relatesto the hydraulic circuit including a control valve consisting of a bypass line and orifices to control the flow of hydraulic fluid in extending or withdrawing the piston for lowering or raising the pivotally mounted offset cutter apparatus.

BACKGROUND. OF THE INVENTION Prior art and presently commercially available offset cutter control devices prior to the present invention have provided for manual means for raising and lowering the offset cutter, or for separately provided hydraulic circuits for raising and lowering the pivotally mounted offset cutter, but there are no clearly known means for singularly providing hydraulic circuit controls from a prime pump of the circuit for controlling a rotary cutters position and rotation. I

BRIEF SUMMARY OF THE INVENTION An object and advantage ofthe invention is to provide a hydraulic circuit for a pivotally mounted offset cutter having, unique featuresaccording to the best mode of the invention, consisting of a bypass line and four orifices for the control valve. One pair of orifices provides a circuit for the mainpressure line to the motor and mayinclude a bypass line-ywith pressurerestricting orifices therein. The other pair of orifices provides. circuit flow to the hydraulic cylinder and piston for extending or retractingthe piston within the off by the valve to allow oil'flow through the bypass line at a limited or reduced rate,,as determined by the size of the orifices, for enabling the motor to continue operating whilethe piston of, the hydraulic cylinder is functioning. A backpressure .builds up behind the orifices and is directed by the control valve to the hydraulic cylinder for causing the. piston .to operate accordingly for either raising or lowering, depending on the oil flow direction therein, to extend or retract the piston for actuating a pivotal arm and accordingly thereby raising or lowering the offset rotary cutter housing and blade assembly.

lt istherefore a furtherobject of the invention to provide operation of the motor underrestrictive conditions such thatthe. only time the. motor operates under such restrictive conditions is when the control valve is actuated to the RAISE or LOWER position.

An additional object of the invention is to provide restricted orificemeans in the pressure lines to the cylinder and piston apparatus for limiting the. rate at which the hydraulic cylinder extends or is withdrawn in the cylinder.

Another object of the invention is to provide automatic and singular means for a hydraulic circuit for a motor and a hydraulic control cylinder and piston arrangement in raising or lowering an offset rotary cutter housing and blade assembly.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the invention will become apparent upon full consideration of the following detailed description and accompanying drawings in which: 7

FIG. 1 is a perspective view from the rear side of a tractor and detached therefrom an offset rotary cutter housing andan blade assembly apparatus embodying a form of the invention;

FIG. 2 is a hydraulic circuit for the hydraulic offset cutter according to the invention, showing how the offset rotary cutter housing may be raised, lowered or held in position, and how the motor at alltimes is used to drive the blade assembly accordingly; and

FIG. 3 is a partial view of a hydraulic circuit showing a modification of the circuit of FIG. 2 according to anotherpreferred embodiment of the invention.

DETAILED DESCRIPTION Referring now to the drawings, there is shown a tractor 10 with a hitch l2 and a rotating drive shaft 14.

There is provided a frame structure 16 adapted to be secured to the hitch 12 and on which there is pivotally mounted a rotary cutter housing 20. The drive shaft 14' hydraulicfluid by a pressure line 38 terminating in an orifice 40. Within the valve 30 is avalve element or slider 42 for the control valve for selectively providing various flowpaths through the control valve. The valve slider is actuated by astem 44 which, in turn, is displaced by a control valve lever orhandle 46 which is pivotally mounted on the frame and can be manually moved or displaced by the tractor operator movingthe handle, as required. When the control handlet46 is in the mid position, the high pressure fluid passing throughorifice 40 continues through an opening or recess 50 inthe slider 42, and then passes through the high pressure line 52 to a hydrauli-cmotor 54 for performing rotation action of a blade assembly 56 mounted within the rotary cutter housing 20. As shown in the drawings, the rotary cutter [housing is mounted by pivot means 60, and may be held in any of various positions by the displacement or movement and positioning of a the control arm 62 which is pivotally mounted at pivot. The control arm 62 holds the rotary cutter housing 20 by means of an adjustable chain 66. As the hydraulic fluid in the high pressure line drives the motor54, the hydraulic fluid used by the motor is carried off by an oil-return line 68 which passes the oil orfluid to a filter 70 which is in turn connected to the oil reservoir 32 which shows oil 72 collected up to a given level. The reservoir has a filler cap 74 to allow the addition of oil to the'hydraulic system, as desired,'and the reservoir is provided with a filter 76 to pass by gravity flow oil from the reservoir through a manual valve 78 and thence through a line 80 to the drive pump 26. The drive pump is driven by the drive shaft 14, as described above, and presents the oil under high pressure through a main pressure line 38, as described above.

When the control valve handle 46 is in its raised position 82 shown in dotted line, the slider 42 is displaced upwardly for the hydraulic fluid to pass from the orifice 40 through a recess 50 to a control line a control line 88. The control line 88 carries the high pressure hydraulic fluid to the right chamber of a hydraulic cylinder 90 which drives a piston 92 leftward for impressing hydraulic flow in the control line 94 so that excess fluid in line 94 is passed through a recess 96 in the slider 42, and the excess fluid is passed through a valve return line 98 to the oil reservoir 32.

The piston 92 being extended leftward causes a control rod 102 acting through a pivot-linkage connection 104 to cause the control arm 62 to be raised and thus raise the position of the rotary cutter housing 20. When the rotary cutter housing reaches a desired or selected position, the control valve handle 46 is returned to a mid position for displacing the slider 42 so that hydraulic fluid cannot escape from the control line 94, and thus hold the piston 92 in place resulting in fixing the position of the rotary cutter housing 20.

When the control valve handle 46 is in the raised position, fluid passing through the control lines 88 and 94 is impeded in its velocity by means of pressurerestricting orifices 108 that limit the rate at which the piston 92 in the hydraulic cylinder 90 extends or contracts.

When the control valve handle 46 is in a lowered position 112, as shown in FIG. 2, the slider 42 is accordingly lowered and the fluid flow in the recess 50 from the main pressure line 38 then passes to the control line 94 to exert the piston 92 in a rightward direction, resulting in lowering the control arm 62, dropping the chain 66, and respectively lowering the rotary cutter housing 20 until the control valve handle is returned to the mid position.

When the control valve handle 46 and the slider 42 are in either the raised or lowered position, and during which time the piston 92 is traversing in a given direction a portion of the length of the hydraulic cylinder, fluid is still applied through the pressure line 52 to the motor 54 in reduced magnitude by means of the bypass line pressure-restricting orifice 114. Thus, when the slider 42 is in either the raised or lowered position, fluid passing through the opening or recess 50 contacts the wall or chamber containing the slider 42, and is then constrained to follow through the pressurerestricting orifice 114 forming a bypass line and thus allowing fluid at reduced pressure to traverse the pressure line 52 for driving the motor 54.

While it may be expedient to provide the opening or recess 50 and the pressure-restricting orifices 114 in the slider, it is also within the purview of the invention to provide an arrangementthat would place the bypass line and the pressure-restricting orifice exterior to the slider 42. Thus in FIG. 3, there is shown the construction of a bypass line arranged to connect the main pressure line 38 to the pressure line 52, and in which there are at least 'one or more pressure-restricting orifices 122. The size of the orifice 122 allows the buildup of back pressure behind the orifices and provides means for directing a fluid flow by the control valve to the hydraulic cylinder for causing it to operate in lieu of the main pressure line being a bleeder line. Thus the size of the orifices determines the rate of flow of fluid around the control valve at a determined and limited rate enabling the motor to continue operating and, as well, performing the function of raising or lowering the rotary cutter housing 20.

It is seen that the unique features of the hydraulic circuit for the hydraulic offset cutter enable a common drive pump driven from the drive shaft of a tractor connected by being hitched to an offset cutter to provide singular means for selectively operating the control cylinder from a control valve, and at all times operate the motor for driving the rotary cutter and the associated blade assembly.

The arrangement of the orifices 108, 114, 122, in the pressure lines 88,94 and in the opening 50 or in the bypass line 120, respectively, provide a 500 psi back-up pressure in the parallel hydraulic lines to the motor and the hydraulic cylinder. The backup pressure of 500 psi is exemplary only, and may be more or less than this in other preferred embodiments.

Various arrangements of lifting arms or control arms 62 are contemplated within the purview of the invention so that one of ordinary skill in the mechanical art can arrange and adapt the hydraulic cylinder 90, the rod 102, the control arm 62 and the link or chain 66 connected to the rotary cutter housing, and may RAISE and LOWER the housing by actuating the piston 92 so that the housing may pass through a sweep of approximately In this way, the complete offset rotary cutter is advantageously and especially practicable for cutting along ditches and banks, as well as in the straightaway. This is accomplished without belts, pulleys, or other mechanical drives and clutch mechanisms, and the hydraulic system is operated independent from the tractor hydraulic system. A

The complete offset rotary cutter embodying the present invention allows for cutting of inclined terrain, cutting or trimming sides of hedges and overhanging trees by cutting a vertical swath. Also the use of the invention provides for cutting ditch banks and slopes in stride. The lateral cutting positions extend to 90 up and 90 down with, according to a preferred embodiment, a maximum reach from the centerline of the tractor to outside of the cutter 9 to 10 feet.

Additional embodiments of the invention in this specification will occur to others and therefore it is intended that the true spirit of the invention be limited only by the appended claims and not by the embodiments-described hereinabove. Accordingly, reference should be made to the following claims in determining the true spirit of the invention.

What is claimed is:

I. An improved hydraulic circuit for a pivotally mounted offset cutter apparatus comprising an offset rotary cutter;

a hydraulic drive pump and a hydraulic motor in a hydraulic circuit with the pump for operating said offset cutter;

a control valve in said hydraulic circuit relating with said pump and said motor, and 5 a hydraulic piston and cylinder in circuit relation with said control valve for said piston upon actuation by said control valve to hold, raise and lower said offset cutter, and said control valve including a valve slider for said control valve for selectively providing (1) a normal flow path through the con trol valve to drive the motor and blocking flow in the circuit of the hydraulic cylinder, (2) a raise flow path through the control valve to actuate the piston to raise the offset cutter, and (3) a lower flow path through the control valve to actuate the piston to lower the offset cutter, said control valve having a bypass line including at least one pressure-restricting orifice allowing flow to the motor at a reduced rate in operating said offset cutter.

2. The invention of claim 1 wherein said valve slider includes said bypass line and including a restrictive orifice path essentially operative only when the raise flow path or the lower flow path is operative.

3. The invention according to claim 2 wherein said control slider is provided with a control valve lever.

4. The invention according to claim 2 wherein said circuit includes an oil reservoir to collect oil flow from the low pressure side of said motor and a return line from said control valve.

5. The invention according to claim 2 wherein said offset cutter is significantly counterbalanced by oil in said reservoir.

6. The invention according to claim '2 wherein said offset cutter is supported by manually adjustable means provided to selectively re-position the orientation of the offset cutter.

7. The invention according to claim 2 wherein filter means is provided in the oil return line from the motor to the reservoir.

8. The invention according to claim 2 wherein valve means is interposed between the reservoir and the drive pump.

9. The invention according to claim 1 wherein said bypass line is external of the control valve and where said bypass line includes a restrictive orifice path essentially operative only when the raise flow path or the lower flow path is operative.

10. The invention according to claim 1, wherein the bypass line is interiorly disposed within the control valve by said bypass being structured as a recess on said valve slider. 

1. An improved hydraulic circuit for a pivotally mounted offset cutter apparatus comprising an offset rotary cutter; a hydraulic drive pump and a hydraulic motor in a hydraulic circuit with the pump for operating said offset cutter; a control valve in said hydraulic circuit relating with said pump and said motor, and a hydraulic piston and cylinder in circuit relation with said control valve for said piston upon actuation by said control valve to hold, raise and lower said offset cutter, and said control valve including a valve slider for said control valve for selectively providing (1) a normal flow path through the control valve to drive the motor and blocking flow in the circuit of the hydraulic cylinder, (2) a ''''raise'''' flow path through the control valve to actuate the piston to raise the offset cutter, and (3) a ''''lower'''' flow path through the control valve to actuate the piston to lower the offset cutter, said control valve having a bypass line including at least one pressure-restricting orifice allowing flow to the motor at a reduced rate in operating said offset cutter.
 2. The invention of claim 1 wherein said valve slider includes said bypass line and including a restrictive orifice path essentially operative only when the ''''raise'''' flow path or the ''''lower'''' flow path is operative.
 3. The invention according to claim 2 wherein said control slider is provided with a control valve lever.
 4. The invention according to claim 2 wherein said circuit includes an oil reservoir to collect oil flow from the low pressure side of said motor and a return line from said control valve.
 5. The invention according to claim 2 wherein said offset cutter is significantly counterbalanced by oil in said reservoir.
 6. The invention according to claim 2 wherein said offset cutter is supported by manually adjustable means provided to selectively re-position the orientation of the offset cutter.
 7. The invention according to claim 2 wherein filter means is provided in the oil return line from the motor to the reservoir.
 8. The invention according to claim 2 wherein valve means is interposed between the reservoir and the drive pump.
 9. The invention according to claim 1 wherein said bypass line is external of the control valve and where said bypass line includes a restrictive orifice path essentially operative only when the ''''raise'''' flow path or the ''''lower'''' flow path is operative.
 10. The invention according to claim 1, wherein the bypass line is interiorly disposed within the control valve by said bypass being structured as a recess on said valve slider. 